Radioactivity Review

Transcription

1 Science Section 7- Name: Block: Radioactivity Review. Complete the following table: Isotope Mass Number Atomic Number (number of protons) Number of Neutrons nitrogen sulfur neon- magnesium beryllium carbon- 6 6 neon- fluorine An element is analyzed and found to have a mass number of 37. It contains neutrons in its nucleus. List: a) the number of protons 7 b) the name of the isotope chlorine-37 c) the standard atomic symbol Cl For an isotope containing protons and neutrons, state: a) the atomic number b) the mass number c) the name of the isotope sodium- d) the standard atomic symbol Na. What is radioactive decay? Radioactive decay is the process in which the nuclei of radioactive parent isotopes emit alpha, beta, or gamma radiation to form decay products.

2 5. Identify the missing particle in each of these alpha decay equations. 3 a) Pa Ac 89 + He 9 8 b) Po Pb 8 + α 8 56 c) Lr Md + α 3 d) 89 Ac Fr + α 6. Identify the missing particle in each of these beta decay equations. a) Na Mg + e b) 79 Au Hg + β 5 c) 6 Fe Co + β 6 d) He 3 Li + β What is the symbol for a gamma ray in an equation? γ 8. Explain the changes that occur in the nucleus during each of the following. a) alpha decay b) beta decay c) gamma decay The nucleus loses an alpha particle, which is the same as a helium nucleus. The mass number drops units and the atomic number drops units. The nucleus releases an electron while a neutron turns into a proton. The mass number remains the same while the atomic number increases by one. The nucleus loses excess energy. The mass number and atomic number remain unchanged. 9. Classify each of the following as alpha, beta, or gamma decay: 38 3 a) U Th + He b) Ni* Ni + γ 8 8 c) Na Mg + e 5 d) Ac Fr + α 89 3 e) Pa* Pa + γ f) I Xe + β alpha gamma beta alpha gamma beta

3 . Which of the following shows alpha radioactive decay? 3 A) B C + e 5 3 B) NaCl Na + Cl 6 C) Ni* Ni + γ 8 38 D) U Th + He 9. Which of the following shows beta radioactive decay? A) Fr At + He B) Cs Ba + e + γ 55 6 C) Ni* Ni + γ 8 D) H O H O + O. Which of the following is an example of gamma radioactive decay? A) K* K + γ 9 9 B) Sr Y + e C) Au Ir + α 79 D) Rn Po + He What type of decay occurs in the following reaction? A) alpha B) beta C) gamma D) decomposition Na Mg + e. Which is the correct parent nucleus to give the following products? 5 A) At 85 9 B) Np 93 3 C) Fr 87 3 D) Pa Ac + He 5. How does each of the isotopes of an atom differ? A) in the number of protons B) in the number of electrons C) in the number of neutrons D) in the number of protons, electrons, and neutrons

4 37 6. How many protons and neutrons are in Cl? 7 A) 7 protons, 7 neutrons B) 7 protons, neutrons C) 7 protons, 37 neutrons D) 37 protons, 7 neutrons 7. If an isotope has 55 protons and 8 neutrons, which of the following correctly represents the isotope? 55 A) Pb 8 8 B) Cs C) Cs D) Pb 8 8. Which of the following correctly completes the following radioactive decay? A) e B) γ C) H D) He - Hg Tl + 9. Which of the following correctly completes the following radioactive decay? A) e B) γ C) H D) He Section Pa Ac +. What is a half-life? Half-life is the amount of time required for half the nuclei in a sample of a radioactive isotope to decay.. How does radioactivity provide a method for determining the age of objects? By measuring relative amounts of remaining radioactive material to stable products formed, such as the ratio of carbon- atoms to carbon- atoms

5 Use this information to answer questions and 3: Suppose a 6 gram sample of a certain isotope has a half-life of years.. State what length of time has gone by after: a) two half-lives years b) four half-lives years 3. How many grams of the isotope are left after: a) years 3 g b) years 6 g c) three half-lives 8 g. Use the following decay curve for isotope X: a) Estimate the half-life of isotope X., years b) What percentage of the original isotope remains after 5 years? 8 % c) How many years does it take for the isotope to be reduced to about percent of its original quantity? 65, years d) How many half-lives have gone by after 6 years? 3 half-lives e) What is the age of volcanic rock containing element X after two half-lives?, years

6 Refer to the Common Isotope Pairs Chart in your Data Pages. 5. Uranium-35 is a radioisotope. What is the daughter in the isotope pair in which uranium-35 is the parent? lead-7 6. What is the half-life of thorium-35? billion years 7. Which radioisotope decays faster, uranium-38 or rubidium-87? uranium When a sample of volcanic rock is formed it contains potassium- but no argon-. When the rock is analyzed later, it contains equal amounts of potassium- and argon-. How old is the rock?.3 billion years ( half-life) 9. What is a half-life? A) the time required for nuclei to undergo nuclear fusion B) the time required for nuclei to undergo nuclear fission C) the time required for half the nuclei in a sample to decay D) the time it takes for an isotope to react with any other substance to produce a new compound 3. The carbon- isotope has a half-life of 573 years. What percent of carbon- isotope will be present after 7 9 years? A).5 percent B) 5 percent C) 5 percent D) percent 3. A g sample of potassium- undergoes radioactive decay until.5 g of potassium- is present. How many half-lives have occurred? A) B) C) D) 3 3. Suppose a meteorite is analyzed and found to contain equal amounts of uranium-38 and lead-6. How long ago did the meteorite form? A) 7 million years B) million years C).5 billion years D) 9 billion years

7 33. What is carbon dating? A) the exact age of a sample of carbon B) the process of determining the time required to complete the carbon cycle C) the process of determining the age of an object by measuring the amount of carbon- remaining in that object D) the process of looking for fossils from specific time periods and determining the age of the carbon sample relative to the fossil 3. If a g rock sample of isotope K undergoes two half-lives to make daughter 9 isotope 8 Ar, what is the mass of the total sample at the completion of the second half-life? A) g B) 5. g C).5 g D).5 g If you start with g of isotope 9 U, what mass of this parent material will be left after four half-lives? A) 5 g B) 5 g C).5 g D) 6.5 g 36. After three half-lives have passed for carbon-, a. g sample remains of the parent isotope. What mass of the parent isotope was originally present? A).5 g B) 8. g C) 6 g D) 3 g

8 37. Scientists have discovered a new isotope (X). Using the data they collected, a graph was produced to show the percentage of the isotope remaining over time. Using this information, what is the half-life of this isotope? A) years B) years C) 5 years D) years 38. A g sample of isotope 6 C decays for 7 9 years. Use the Common Isotope Pairs chart in your Data Pages to find the half-life of this radioactive sample. Determine the total mass of daughter isotope N that would be produced. 7 A) 8.75 g B) 7.5 g C).5 g D).5 g Section What is a fission nuclear reaction? A fission nuclear reaction is the process by which a large nucleus splits into two pieces of roughly equal mass, accompanied by the release of large amounts of energy.. What two quantities do not change during a nuclear reaction? The sum of the mass numbers; the sum of the charges (represented by atomic numbers). Find the indicated daughter nucleus. a) n + U + Mo + 3 n + energy 35 3 b) n + U Rb 37 + Cs + 3 n + energy c) n + U 3 + Nd + 3 n + energy Sn 9 93 Ge

9 . What happens in a nuclear chain reaction? A chain reaction is a reaction in which the products of the reaction trigger more reactions in a selfsustaining process 3. Why are hazardous wastes from nuclear reactors an ongoing issue in society? It takes half-lives (thousands of years) before the material reaches safe levels of radioactivity.. What is nuclear fusion? Fusion is the joining of two small atomic nuclei to make a larger one, usually involving the release of a large amount of energy. 5. Where does most nuclear fusion occur in our solar system? In the Sun 6. What is nuclear fission? A) the process in which two low mass nuclei join together to make a more massive nucleus B) the process of cell division that results in two new cells that are identical to their parent cell C) the splitting of a massive nucleus into two less massive nuclei, subatomic particles, and energy D) the process in which a parent cell splits into two daughter cells of approximately equal size, often occurring in single celled organisms 7. What is nuclear fusion? A) the process in which two low mass nuclei join together to make a more massive nucleus B) the process of cell division that results in two new cells that are identical to their parent cell C) the splitting of a massive nucleus into two less massive nuclei, subatomic particles, and energy D) the process in which a parent cell splits into two daughter cells of approximately equal size, often occurring in single celled organisms 8. Which equation represents nuclear fission? A) K Ca + e + energy 9 B) C 3 H 7 OH + 9O 6CO + 8H O C) H + H He + n + energy - D) n + U Kr + Ba + 3 n + energy

10 9. Which equation represents nuclear fusion? 3 A) I Xe + β B) U Th + He + γ 9 C) H + H He + n + energy D) n + U Mo + Sn + 3 n + energy 5. What is the daughter nucleus to complete the following nuclear fission reaction? A) In 9 5 B) In 9 7 C) In 9 8 D) In n + U Tc n + energy Which of the following is used to control the rate of the chain reaction that occurs in a nuclear reactor? A) Add uranium-35 to the reactor. B) Use fossil fuels (like gas or coal). C) Insert cadmium rods into the nuclear reactor. D) Remove cadmium rods from the nuclear reactor. 5. Which statement about nuclear fusion is not true? A) Two lightweight nuclei join together to form a heavier nucleus. B) A typical reaction showing nuclear fusion is: H + H He + n + energy C) Lightweight nuclei will not release excess energy if the nucleus generated by fusion is heavier than iron. D) There are many commercial fusion reactors in the world. Canada has a series of them called CANDU reactors. 53. Which of the following statements applies to nuclear fission? A) Nuclear fission produces clean energy with very little waste. B) Unstable nuclei release a huge amount of energy when they split. C) Heavy, unstable nuclei join together into one new, larger nucleus. D) A typical reaction for nuclear fission is: 3 3 H + H He + n + energy

11 5. Which of the following statements applies to nuclear fusion? A) All fusion reactions release massive amounts of energy. B) Unstable nuclei release a huge amount of energy when they split. C) A typical reaction for nuclear fusion is: 35 n + U Kr + Ba + 3 n + energy D) A fusion reaction is used in modern nuclear weapons to generate most of the energy released in the blast. 55. How can a nuclear reaction be induced? A) by bombarding a nucleus with alpha particles, beta particles, or gamma rays B) by heating the reaction with your lab Bunsen burner C) by inserting cadmium rods into the nuclear reactor D) by burning the nucleus using oxygen 3 56